P0155O2 Sensor Heater Circuit Bank 2 Sensor 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The upstream oxygen sensor on bank 2 (sensor 1) has its own electric heater. P0155 is the bank 2 counterpart of P0135: the heater current is outside its window or the driver voltage does not follow the command. GM fails it outside 0.3–3.1 A (8 s or 8 of 10 samples, two trips); Ford outside roughly 0.22–0.465 A minimum to 3 A, with related codes for heater temperature control (P0050) and resistance (P0059). Closed loop on bank 2 then starts late after a cold start, and the sensor checks are suspended. P0135 together with P0155 points to a shared supply or fuse.
- What you may notice
- Check engine light on
- Higher emissions and consumption after cold start
- Follow-up codes P0153/P0154 possible
- Likely causes
- LikelyHeater element of the sensor burnt out (sensor must be replaced)
- PossibleFuse or relay of the heater supply faulty
- PossibleHeater wiring or connector open, corroded or shorted
- RareHeater driver in the control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €5 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.